I mostly use the Exos 48, but have a 58 for bulkier loads (longer trips or winter.) I really, really like them both. As mentioned above, I have no problems with a single compartment - my tent, kitchen and pad live on top of the sleeping bag. When I hit camp, I set up the tent and pad, put the kitchen beside the tent, and pull out the bag, so it's a logical packing order. I never need the bag during the day, so there's no need to access it. Besides, as someone else mentioned, I view zippers as potential weak points.

I tried an Atmos 50, but found it too heavy and overbuilt for the lightweight loads I carry (16-18 pounds, including food and a liter of water, for a weekend.) I replaced it with Exos 48, and couldn't be happier with my choice.

I find the Exos packs have just enough outside pockets to hold everything I need during the day, and no gimmicky features I don't need (except for a hydration sleeve and the goofy little stow-on-the-go loops. Unlike Nolte and Redford, I use my poles for walking, not pack decoration. )